Post Photobucket Re-Boot................
Thankfully they gave no trouble in Scotland, except for a slight rattle. So when we got home I nipped them up. But one side just let go. This seems to be a brass casting and the threaded stud was aerated......................
The threads are a bit offine at the base and clearly the thread locking found the weakness.

So nothing for it but to cut the stud flat and centre-punch ready to drill out.

After drilling.............

Next I cut half the head off two bolts........quicker than filing.

The thinned down bolts were threaded through and araldited in place.



I may pad the back with some neoprene or leather before refitting.
UPDATE: I added some leather trim at the back of each bracket so that the nuts wouldn't damage the B panel leather trim.
So the moral of this story is - don't overtighten!